Computed Tomography (CT) is an imaging technology that uses computer-processed X-ray beams to produce tomographic images of specific areas of a scanned object. Each x-ray beam comprises bundles of energy (or “photons”) which, depending on the structure of the imaged material, may pass through, be absorbed by, or be redirected (i.e., scattered) by the structure. The degree to which an x-ray beam is reduced by an object during imaging is referred to as attenuation.
In order to differentiate two adjacent objects in a CT scan, there must be a density difference between the two objects. Where such a density difference does not naturally exist in the anatomy, a contrast enhancement material may be injected into the subject to create an artificial density difference in targeted areas to facilitate enhanced imaging. For example, a high density fluid may be used to fill the vasculature to differentiate it from the surrounding tissue.
There are many different types of contrast enhancement materials generally known in the art, each providing unique benefits. However, with conventional systems it is challenging to use multiple types of contrast enhancement materials simultaneously. For example, materials such as gadolinium and iodine have traditionally been used for vascular visualization. For tissue enhancement, materials such as nanoparticles may be used to bind to an area of interest (e.g., macrophages to target anatomical “hot spots” of chronic inflammation). Unfortunately, these nanoparticle contrast agents require some time before binding at the site of interest, during which time the vascular contrast agents are washed out and are no longer useful for imaging. This leads to a very low contrast-to-noise ratio (CNR) for tissue and vasculature.
Accordingly, it is desired to produce a technique for simultaneously acquiring image data corresponding to multiple contrast agents using a single scan.